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Database

Out-of-bounds read

Need

Prevention of out-of-bounds read vulnerabilities

Context

• Usage of Go 1.16 for developing high-performance and scalable applications

• Usage of Gin framework for building web applications in Go

Description

1. Non compliant code

package main

import (
	"fmt"
	"github.com/gin-gonic/gin"
)

	r := gin.Default()...

In the above code, we have a simple Gin based HTTP server that has a single GET endpoint "/read". This endpoint reads an index from the query parameters and uses it to access an element in the `data` array. The vulnerability lies in the fact that there is no boundary checking for the index value. This means, if a user provides an index that is outside the bounds of the `data` array, the application will attempt to read memory that it shouldn't, leading to an out-of-bounds read vulnerability. For instance, if a user sends a GET request to "/read?index=10", the application will attempt to access `data[10]`, which is outside the bounds of the `data` array (which only has indices 0-4). This will result in an out-of-bounds read, which can lead to undefined behavior and potential security risks.

2. Steps

• Validate the input to ensure it is within the bounds of the data array.

• Check if the index value is a valid integer.

• Handle any potential errors when converting the index value to an integer.

• Implement proper error handling to handle out-of-bounds read scenarios.

• Return an appropriate response to the client if the index is out of bounds.

3. Secure code example

package main

import (
	"fmt"
	"github.com/gin-gonic/gin"
	"net/http"
	"strconv"
...

The updated code includes several checks to prevent out-of-bounds read vulnerabilities. 1. **Input Validation**: The code checks if the index value provided in the request is a valid integer. If the `strconv.Atoi` function returns an error, it means that the index value is not a valid integer. In this case, the code returns a `400 Bad Request` response with an error message "Invalid index value". 2. **Bounds Checking**: The code checks if the index value is within the bounds of the `data` array. If the index value is less than 0 or greater than or equal to the length of the `data` array, it means that the index is out of bounds. In this case, the code returns a `400 Bad Request` response with an error message "Index out of bounds". These checks ensure that the system only reads data within the intended buffer, preventing out-of-bounds read vulnerabilities.

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